Field of the Invention
The present invention relates to a three-dimensional measurement apparatus for capturing images of a workpiece from two or more view points to make a three-dimensional measurement or view the workpiece stereoscopically, and a robot system including the same.
Description of the Related Art
Conventionally, a three-dimensional measurement apparatus has been widely used, which captures images with a plurality of cameras in making a three-dimensional measurement or stereoscopic viewing to acquire three-dimensional information in order to make a three-dimensional measurement from the three-dimensional information. As the three-dimensional measurement apparatus, for example, a stereo method is widely known, which extracts feature points from captured two images, respectively, and establishes correspondences among the extracted feature points to make a three-dimensional measurement by the principle of triangulation.
In the meantime, in the field of digital cameras using an image sensor such as CCD or CMOS, digital cameras having a partial cropping function for presetting a range of pixels to be read on the image sensor to read only necessary pixels have become common in recent years. The partial cropping function can reduce the data volume to be handled, and hence has the advantage of being able to perform transfer of image data and image processing at a higher speed than the case of using all pixels.
However, the above-mentioned partial cropping function is required to preset the range of reading pixels on the image sensor. Therefore, for example, when objects are conveyed along a production line in such a state that the objects vary in position, there arises a problem of making it difficult to adapt the partial cropping function to the state.
On the other hand, as a method of cropping an area from a stereo image, there is proposed a three-dimensional measurement apparatus which, after acquiring a first image and a second image, finds a portion similar to the first image from the second image to set a cropping range from the similar portion (see Japanese Patent Application Laid-Open No. 2005-045328).
However, since the three-dimensional measurement apparatus described in Japanese Patent Application Laid-Open No. 2005-045328 sets the portion similar to the first image as the cropping range of the second image after acquiring both of the first image and the second image from a camera, there is a problem that the time of transferring images from the camera cannot be reduced. In other words, the benefits of the partial cropping function in the above-mentioned digital camera cannot be derived.
Therefore, it is an object of the present invention to provide a three-dimensional measurement apparatus for reducing the amount of information to enable speeding up of image processing, and a robot system including the same.